The roots of your teeth may be bent, curved, or mis-shapened as a result of trauma, or some disturbance to the root forming tissues during root development.
This is often only discovered during routine X-rays of your jaws, as the teeth may appear quite normal outwardly if the tooth crown is not deformed.
When the roots are severely bent, it would be difficult for the teeth to erupt properly. They may end up deflected off the normal path of eruption, or end up impacted against a neighbouring tooth. It may be difficult for the orthodontist to straighten these teeth completely.
Severely curved roots also present a problem to the dentist should they require root canal treatment in future, (e.g. due to a tooth abscess) because the curved root canals are less easily accessible for cleaning and disinfection.